1. Field of the Invention
The present invention generally relates to determining dynamic care areas.
2. Description of the Related Art
The following description and examples are not admitted to be prior art by virtue of their inclusion in this section.
Inspection processes are used at various steps during a semiconductor manufacturing process to detect defects on wafers to promote higher yield in the manufacturing process and thus higher profits. Inspection has always been an important part of fabricating semiconductor devices. However, as the dimensions of semiconductor devices decrease, inspection becomes even more important to the successful manufacture of acceptable semiconductor devices because smaller defects can cause the devices to fail.
While it is important to detect defects on wafers, it is also important to determine the origin of the defects so that the cause of the defects can be eliminated. One current method of tracking the origin of defects is defect source analysis (DSA). In this method, the defect locations for inspection step 1 and step 2 (and any following steps) are overlaid on a common coordinate system, and common defects (within some distance tolerance) across steps are flagged. By noting the first (i.e., earliest) step in which a defect was detected, its source can be determined.
One disadvantage of the currently used method is that very often the thresholds set at each step are conservative (for stability purposes). Therefore, the signal of a defect detected at a later inspection step, though present in that location at an earlier step, may not be flagged as a defect at that earlier step. In this manner, inspection results for the location at the earlier inspection step may simply not exist. Secondly, no use is made of the data at one step to affect the recipe used on that wafer at a subsequent step. For example, if some systematic (i.e., repeater) signal is present at certain locations, this information is not used at the next inspection step to, for example, enhance the possibility of detecting a defect event at the next step.
Accordingly, it would be advantageous to develop methods and systems for more efficient tracking of defects from one step to another.